Circuit breaker with an automatic and manual release



y 1942- G. BGTTINGER ET AL ,290,367

CIRCUIT BREAKER WITH AN AUTOMATIC AND MANUAL RELEASE Filed Oct. 31, 19402 Sheet s-Shet 1 ATTORNE July 21, 1942- G. BOTTINGER ETAL CIRCUITBREAKER WITH AN AUTOMATIC AND MANUAL RELEASE Filed Oct. 31, 1940 2Sheets-Sheet 2 INVENTORS Gntfia-B'itizgerazd [Kant fizz/ye.

ATTORNEY gggNEssFs: I

Patented July 21, 1942 ICE CIRCUIT BREAKER WITH AN AUTOMATIC AND MANUALRELEASE Giinther Biittinger, Berl Kurt Prange, Berlinin-Siemensstadt,and Spandau,

Germany, as-

signors to Westinghouse Electric & Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application October 31 InGermany 7 Claims.

The invention relates to a circuit breaker with an automatic and manualrelease and provided with a toggle mechanism. The present inventioncovers a circuit breaker which is an improvement and further developmentof the circuit breaker mechanism disclosed in the copending applicationof Hans H. Willmann, Serial No. 157,028, filed August 2, 1937, nowPatent No. 2,217,462, issued October 8, 1940, and assigned to theWestinghouse Electric & Manufacturing Company. In the circuit breakermechanism disclosed in the aforementioned copending application, theknee pivot of the toggle is guided in an elongated slot of a partintegral with the manually operable handle for closing the breaker, oneend of the toggle being pivotally connected to a latching levercontrolled by the release members and the other end thereof cooperatingwith the switch lever. The latching lever is releasably held in theclosed circuit position of the circuit breaker by a holding lever havingunequal arms, the longer arm cooperating with the latching lever and theshorter arm being actuated by the release members. The pressurebetweenthe latching lever and the holding lever acts on the pivot of theholding lever. This switch mechanism presents the advantage over theswitch mechanism of the known circuit breakers in that the time lag ofthe release is small, and the breaker can readily be manufactured at arelatively low cost on a large scale.

An object of the present invention is to provide a circuit breaker of avery compact design while ensuring the greatest possible interruptingcapacity without impairing the reliability of operation. This may beaccomplished according to the invention by designating the switchmechanism in the following manner: The switch lever is rotatably mountedin the neighborhood of the shortest possible line connecting the pivotof the latching lever and the base and is coupled through anintermediate link with the end of the toggle which is connected to apivoted guide link. The switch lever extends substantially parallel tothe base in the direction tawards the shortest line that can be drawnfrom the end of the toggle cooperating with the switch lever to thebase. With the switch mechanism according to the invention the switchlever need only carry out very small control motions brought about bythe toggle. In order to attain a relatively large distance of contactseparation, the switch lever is made long. Since the switch lever isarranged substantially in parallel relation to the base, the circuitbreaker has a relatively small height notwithstanding the long switchlever. Besides the small height, the circuit breaker has a small basesurface, since the switch lever need not be any longer than the togglewith its locking parts.

, 1940, Serial No. 363,706

August 3, 1939 (Cl. 2001l6) The small dimensions of the circuit breakerare also due to the fact that the stationary contact cooperating withthe switch lever is secured to a bar conductor which extends parallel tothe base in the direction towards the shortest line that can be drawnfrom the pivot of the latching lever to the base, and the conductor hasa gap therein bridged by a bimetallic strip which is disposedsubstantially parallel to the base. The design of such a circuit breakermakes it possible not only to arrange the bimetallic strip in a verysmall space but also to provide very simple current paths within thecircuit breaker.

Of particular advantage is the provision of a gap or space between thefree end of the bimetallic strip and the holding lever controlledthereby, which holding lever latches the latching lever of the toggle.The bimetallic strip must when heated traverse the gap or spac before itcomes into engagement with the holding lever.

By designing the circuit breaker as described above oscillations of thebimetallic strip caused by the vibrations of the circuit breaker cannotfalsely release the switch mechanism so that the circuit breakeraccording to the invention is protected to a high degree againstvibrations.

The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims. The invention itselfboth as to structure and operation, together with additional objects andadvantages thereof,

will be best understood from the following detailed description of oneembodiment thereof when read in conjunction with the accompanyingdrawings in which:

Figure l is a partly schematic view of a circuit breaker embodying thefeatures of the present invention, the breaker being shown in opencircuit position,

. Fig. 2 is a view similar circuit breaker in closed Fig. 3 is avertical plete circuit breaker with the invention,

Fig. 4'is an end elevational view of the circuit breaker shown in Fig.3, and

Fig. 5 is a side elevational view of the circuit greaker as view fromthe right-hand side of The invention will first be explained byreference to Figs. 1 and 2. Fig. 1 shows the circuit breaker in the opencircuit position and Fig. 2 in the closed circuit position. Thereference numeral I designates the base of the circuit breaker on whichis mounted the switch mechanism. A stationary contact 2 cooperates witha movable contact 3 secured to a pivoted switch lever 4. The circuitbreaker is adapted to be manually closed by means of a closing pushbutton 5. In-

to Fig. 1 but showing the position,

sectional view of a comconstructed in accordance tegral with the closingpush button 5 is a part I provided with an elongated slot 6 and havingintegral therewith a rod-like extension 8. The push button .5 and therod-shaped extension 8 are guided along the stationary transverse walls9. lfl.

In the elongated slot 6 moves the knee of a toggle consisting of thetoggle links H, l2.

One end of the toggle is pivotally connected to 4 through a couplingmember IS. The member l9 and switch lever 4 are rotatably mounted on thestationary pivot 20. Between the member l9 and the switch lever 4 acts aspring 2| wound around the pivot 20. One end of the spring pressesagainst the member l9 and the other end against the switch lever 4 sothat the spring tends to move the switch lever against the stationarycontact 2.

An essential feature of the switch mechanism according to the inventionis the fact that the pivot of the switch lever 4 is arranged in theneighborhood of the shortest line connecting the pivot M of the latchinglever l3 and the base I. From here the switch lever extendssubstantially parallel to the base i in the direction towards theshortest line that can be drawn from the end of the toggle cooperatingwith the switch lever to the base. In this manner it is possible toaccommodate-in the circuit breaker a relatively long switch lever. Sincethe switch lever is very long the break distance between. the contacts 2and 3 is great. Owing to the great break distance the circuit breakerhas a great interrupting capacity. In order to attain this great breakdistance the switch lever need not be any longer than the length of theupper part of the switch mechanism. Owing to the parallel arrangement ofthe switch lever and the linkage to the base I, the height of thecircuit breaker can be made very small. Since the upper part of theswitch mechanism does not require a great width, the design of theswitch mechanism according to the invention is such as to obtain a verycompact circuit breaker.

The spring 2| wound around the pivot 20 acts r not only as a contactpressure spring so as to ensure a reliable contact pressure but alsoserves to bring about a snap movement when the contacts are closed. Thequick make action of the contacts is accomplished with the aid of ahook-shaped member 22 which is pivotally connected to the switch lever 4and is under the action of a biasing spring and cooperates with thestationary transverse wall ID. The hook shaped member 22 is adapted tobe moved out of engagement with the wall I by the part 'I of the pushbutton 5 as the push button 5 approaches closed position, thus releasingthe switch lever 4 for closing movement by the spring 2|.

Besides the spring 2| there are two further springs in the switchmechanism. These two springs are wound around the stationary pivot l3.One spring 23 is the circuit opening spring, one end of which pressesagainst the stationary frame and the other end against the toggleconpivot sisting of the member l2 and the intermediate link H. The otherspring 24 is a lifting spring for returning the closing push button 5outwardly to open position when the breaker is tripped. One end of thisspring presses against the stationary frame and the other end isconnected to the part I of the push button 5.

A pin 5| on the member l9 extends laterally therefrom and is disposed toengage a portion of the switch member to the left of the pivot 20 whenthe member I9 is moved in a counterclockwise direction by the openingspring 23, upon opening operation of the breaker. The pin 5| picks upthe switch member 4 after the member l9 has rotated a small amount in acounterclockwise direction and causes the switch member 4 to be rotatedto open position shown in Fig. 1 with the member 19, by the action ofthe circuit opening spring 23.

Between the switch lever 4 and the base I is arranged a conductor bar 25secured to insulating supports on the base I. The conductor bar isarranged above the base I and carries the stationary contact 2. Fromthis contact the conductor bar 25 extends in the direction towards theshortest line connecting the pivot l4 of the latching lever l3 and thebase I. The conductor 25 is interrupted as indicated at 26. This gap isbridged by a U shaped bimetallic strip 21 which is arranged according tothe invention in parallel relation to the base I and has a free portionof substantial length extending laterally from the conductor 25. Thefree end of the bimetal strip 21 is bent back on itself as shown inFigs. 4 and 5, and the strip is arranged to deflect outwardly, i. e.,away from the base I, to trip the breaker by moving the holding leverl5. In this manner thebimetallic strip is arranged in the circuitbreaker in a very small space. Under certain circumstances a shuntresistance may be arranged in parallel relation in the bimetallic strip21. This shunt resistance is not shown in I the drawings. The end of theconductor 25 opposite to the contact 2 leads to a terminal. From asecond terminal extends a flexible conductor 28 which is connected tothe switch lever 4. The two terminals are not shown in Figs. 1 and 2.

The operation of the switch mechanism according to the invention is asfollows:

In Fig. 1 the switch mechanism is in the open circuit position in whichthe contacts 2 and 3 are spaced from one another. The hook-shaped member22 comes into engagement with the rear side of the stationary transversewall Hi. If the closing push button 5 is depressed the knee pivot of thetoggle ll, 12 is moved in the downward direction and the toggle isextended. As shown in Fig. 2 which indicates the closed circuit positionof the switching mechanism, the toggle is slightly overset. Since thelatching lever I3 is in engagement with the holding lever l5 it cannotrotate and thus forms a support for one end of the toggle H, [2.Consequently, the link it rotates in the counter-clockwise direction.During this rotation the member I9 is rotated in the clockwise directionby the intermediate link H. The switch lever 4 is prevented from beingmoved at first, since the hook-shaped member 22 engages the rear side ofthe stationary plate ll. As soon as the closing push button 5 approachesthe lowest position the part 1 of the pushbutton pushes the hook-shapedmember 22 aside and releases the switch lever 4. The switch lever canthen snap into the closed circuit position in g which the contacts 2 and3 are in engagement.

v bar 39 of the open circuit member 38.

When the circuit breaker is being closed the circuit opening spring 23and the lifting spring 24 becomes stressed. If the bimetallic strip 21is actuated in response to an overload of the circuit to be controlledor if the circuit breaker is brought into the manually operated circuitposition by the open circuit opening member hereinafter described, theholding lever l moves away from the latching lever i3 and re- I leasesthe latter. Upon the release of the latch: ing lever the guide link I6is rotated under the action of the circuit opening spring 23. By thisrotation the member I! and the spring 2| of the switch lever 4 aresnapped, through the intermediate link ll, into' the open circuitposition. At the same time the push button a is raised by the spring 24from its lowest position.

Figs. 3 to 5 show an embodiment of the circuit breaker schematicallyshown in Figs. 1 and z. The base I consists of a sheet having a cavityat the rear and a narrow bottom of rectangular 7 form.

Terminals 29, 30 are mounted on an insulating body 3| at one end of thebase I. From the base extend two side walls 32 and 33 which are spacedfrom each other by the transverse walls 9 and ID. The side wallsare-lined at the sides facing each other with plates 34, 35 ofinsulating material. The side walls and the plates of insulatingmaterial form the bearings for the stationary pivots of the switchmechanism. in order to insulate the switch mechanism with respect to theswitch lever 4, the coupling member I9 is made of insulating material. l

The switch mechanism according to, themvention presents, furthermore,the iollowing advantages.

The holding lever l5 which blocks the latching lever I3 is preferably inthe form of a threearmedlever mounted on the stationary pivot 36. It hasa long arm and two short arms. The long arm cooperates with the latchinglever I3,

the second arm carries an adjusting screw3l opposite to the bimetallicstrip 27. The third arm cooperates with a manually operable circuitopening member 38. The circuit opening member 38 is a push button and isprovided with a bar 39 guided along the wall 33. The nose 40 of the bar39 acts on the short arm of the holding leve'r I5. The stop lever I5 isunder the action of the spring 4| wound around the pivot, 36. One end ofthe spring contacts with the arm of the stop lever carrying theadjusting screw 31 and the other end is connected to the The springtends to move the holding lever l5 into the active zone of the latchinglever l3. The movement of the holding lever in the active zone of thelatching lever is, however, preferably latching lever is kept as smallas possible. The

holding lever has a portion cut away so that when the holding lever ismoved to released position it does not impede movement of the latchinglever IS.

The holding lever l5 and the bimetallic strip 21 are preferablyarrangedwith respect to each other in such a manner that the bimetallicstrip in a cold state is spaced from the adjusting screw 31 of theholding lever. This gap must be traversed by the bimetallic strip whenheated before it comes into-engagement with the holding lever. Owing tothis spacing or gap, oscillations of the bimetallic stripwhich occurwhen the circuit I circuit breaker are avoided upon the occurrence ofvibrations.

If various automatic circuit breakers according to the invention arearranged close to one another it is preferable under certaincircumstances to provide the circuit breaker with a special currentsupply bar 44 connected to the conductor bar.25.

This additional current supply bar 44 is preferably connected to theportion of the conductor 25 arranged between the bimetallic strip 21 andthe terminal3fl. The conductor 44 is preferably arranged in the cavityof the based and brought out at the end of the base opposite to theterminal 30. This additional current supply bar is employed if variousautomatic circuit breakers are to be connected to a common bus bar.

What is claimed is: g I

1. A circuit breaker comprising a base, a pivoted switch arm on saidbase, operating means therefor on said base comprising a pivoted latching lever means for releasably restraining said lever in one position, atoggle pivotally connected at one end to said latching lever, means forguiding I the other end of said toggle for movement in a fixed path,means including alink connecting the guided end of said toggle 'to saidswitch .arm, an operating member for moving the knee pivot ofsaid-toggle to cause said toggle to move said switch arm to closedcircuit position, trip means operable to effect release of said latchinglever to cause movement of said switch arm to open circuit position, thepivot of said switch arm being disposed in close proximity to a linefrom the pivot of the latchirm lever normal to the base, said switch armbeing disposed substantially parallel to the base and extending toward aline drawn from.

the guided endof the toggle normal to the base.

2. A circuit breaker comprising a base, a pivoted switch arm on saidbase, operating means therefor on said base ,comprising a pivotedlatching lever, means for releasably restraining said lever ,in oneposition, a toggle pivotally connected at one end to said latching leverand at the other end to a pivoted guide link, meansineluding a linkconnecting the guided and of said toggle to said switch arm, anoperating member having an elongated slot for engaging.

the knee pivot of the toggle, said operating member being operable tocause said toggle to move the switch arm to closed circuit position,trip means operable to effect release of said latching lever to causemovement of the switch arm to open circuit position, the pivot of saidswitch arm being located in close proximity to a line drawn from thepivot of the latching lever normal to said base, said switch arm beingdisposed substantially parallel to the base and extending in a directiontoward a line drawn from the pivot of the guide link normal to said base3. A circuit breakereomprising a base, a pivoted switch arm on saidbase, operating means therefor comprising a pivoted lever, means forreleasably restraining said lever in one position, a. toggle pivotallyconnected at one end to said lever, means for guiding the other end ofthe toggle for movement in a eluding a link connecting the guided end ofthe toggle to said switch arm, an operating member operable to move theknee pivot of said toggle to cause said toggle to move the switch arm toclosed circuit position, arm being located in close proximity to a linedrawn from the pivot of said lever normal to the base, said switch armextending substantially parallel to said base in a direction toward aline drawn from the guided end of the toggle normal to the base, astationary contact engageable by the switch arm and secured to aconductor bar which lies parallel to the base and extends toward thenormal line from the fixed path, means inpivot of said lever to thebase, said conductor bar having a gap therein, and a strip of bimetallicmaterial bridging said gap and disposed subthe pivot of said switchstantially parallel to said base for effecting release of said lever inresponse to predetermined ,overload'conditions to cause movement of theswitch arm to open circuit position.

4. A circuit breaker comprising a pivoted switch arm, operating meanstherefor comprising a pivoted latching lever, a holding lever forreleasably restraining said latching lever in one position, a toggleconnected at one end to said latching lever and at its other end to theswitch arm, an operating member for moving the knee pivot of the toggleto cause movement of the switch arm to closed circuit position, amanually operable tripping member for moving said holding lever torelease thelatching, lever and thereby cause opening of the breaker, anda birnetal element heated in response to the current of the circuit formoving said holding lever to effect release of said latch.- ing lever inresponse to predetermined overload conditions, said holding lever havingthree arms, one of said arms being engageable with the latching lever torestrain said latching lever, another of said arms cooperating with saidbitoward .a line drawn from the pivot of the latchmetal element, and thethird arm cooperating with said manually operable tripping member, aspring biasing said holding lever into a position in which it engagessaid latching lever, and means, including a stop on said holding leverfor limiting the distance 01' travel of the holding lever within itsrange of engagement with the latching lever.

B. A circuit breaker comprising relatively movable contacts, operatingmeans therefor comprising'a manual operating member operable to closefor moving the knee pivot of said toggle to close the breaker, amanually operable tripping member for moving said holding lever toeffect release of said latching. lever to cause opening or the breaker,a bimetal strip operable in response to predetermined overloadconditions to move said holding lever to effect release of said latchinglever and thereby cause opening of the breaker, a stationary contactengageable by said switch arm, said contact being secured to a'conductorbar which lies parallel to the base and extends ing lever normal to thebase, said conductor bar having a gap therein bridged by said bimetalstrip which is also disposed substantially parallel to said base, thepivot of said switch arm being located in close proximity to a linedrawn from the pivot of the latching lever normal to the base, and saidswitch arm extending substantially parallel to the base and toward aline drawn from the guided end of the toggle normal to the base, saidholding lever having three arms, one of said arms being engageable withsaid-latching lever for restraining said latching lever, another of saidarms cooperating with said bimetal strip, and the third arm cooperatingwith said manually operable tripping member.

7-. A circuit breaker comprising a hollow base plate, a pivoted switcharm on said base, operating means therefor on said base comprising apivoted latching lever, a holding lever'ft': releasably restraining saidlatching lever in one position, a toggle pivotally connected at one endto said latching lever, means for guiding the other end of said togglefor movement in a fixed path, means including a link connecting theguidedend of said toggle to said switch arm, ,an operating member'formoving the knee pivot of said toggle to close the breaker, the pivot ofsaid said contacts, a member releasable to cause opening oi saidcontacts, a holding lever for restraining said releasable member, amanually operable tripping member for moving said holding lever torelease said releasable member, and a bimetal element heated in responseto the current of the circuit and operable in response to predeterminedoverload conditions to move said holding lever to effect release of saidreleasable member, said holding lever having three arms, one of saidarms being engageable with the releasable member to restrain saidmember, anoth er of said arms cooperating with said bimetal element, andthe third arm cooperating with the manually operable tripping member,said bimetal element normally being separated from said holding lever bya predetermined distance through which the bimetal element must movebefore engaging the holding ,lever.

6. A circuit breaker comprising a base, a pivswitch arm being located inclose proximity to a line drawn from the pivot of the latching levernormal to said base, and said switch arm ex tending substantiallyparallel to the base in a direction toward a line drawn from the guidedend of the toggle normal to said base, a stationary contact engageable"by said switch arm,

said contact being secured to a conductor bar which lies parallel tosaid base'and extends toward a line drawn from the pivot of the latchinglever normal to said base, said conductor bar having a gap thereinbridged by a bimetal strip disposed parallel to said base, said bimetalstrip being operable in response to predetermined overload conditions tomove said holding lever to effect release of said latching lever andthereby cause opening of the breaker, and an additional conductor barmounted inside the hollow base and connected at one end to the firstmentioned conductor bar, the other end or said additional bar conductorextending out through the end of said base adjacent which the stationarycontact is located.

GUNTHER no'rrmasa.

KURT PRANGE.

